The engine of a friends Piper apparently developed brass in the oil. They found too many chips in the oil filter to just monitor the oil for the next couple of hours.
It is his first oil change on that aircraft. The documentatiom did not mention any metal before. The engime is about four years old and has around 2000 hours and was generally well cared for, although it has lives as trainer and charter aircraft.
The oil was quite dark after around 20 … 30 hours. My hope would be that we “just” have a problem with an exhaust valve guide and do not need to completely overhaul the engine.
Although we haven’t performed a compression test, there wasn’t any obvious weak cylinders. The engine sounds good and ran good, so we are tending to exclude the bearings.
Does anyone have an other opinion on the presented information or any idea where we should look besides the valve guides? I haven’t seen the engine, yet, but my friend is at the aircraft tomorrow.
Thanks!
Check the part number of the piston pin plugs, some are brass.
If you have the brass type of plugs it is time to take off all the cylinders to look for ridges in the cylinders at oil control ring BDC position.
IF ( and I stress IF this is the case ) at 2000 hours it is likely that the fix will not be worth doing and an overhaul will be the best economic option.
FWIW there is a Lyco service letter around which details what size of chips etc is acceptable for airworthiness purposes. I found this on google.
This is a good article. Also search EuroGA for e.g.
acceptable metal
Unfortunately the compression figure is a poor proxy for the condition of an engine if the engine is breaking up inside. It just tells you the general condition of valves and piston rings.
We usually run our IO360 app. 100-150 hours a year.
Last year I used the aircraft for intensive IR training. I noticed that during this period of intensive use the color of the oil was keeping the transparent fresh oil look way longer than when we just fly the usual few hours a week with longer stops in between.
Even if was only a valve guide, will there be no problem signing off the engine “on condition” above TBO if it has metal in the oil filter? Most shops I know would have a hard time doing that … And although the 360 is probably the most bulletproof engine (of all the typical ones) … after 2000 h as a trainer it might as well be ready for an overhaul …
I find that the oil is pretty dark after say 30hrs. This seems normal.
If an engine is making metal and it is IAW the Lyco SL then technically it can be signed off as airworthy, but the pilot does need to have an “interesting” attitude to risk 
At 2000hrs, it’s time to spend the engine fund, IMHO.
Valve guide material would not find it’s way into the oil system.
The key here is how much metal are we talking about ?
mh wrote:
It is his first oil change on that aircraft.
IMHO, quite likely the seller found same, hence the sale.
